Summary Neuronal reorganization is a critical step in the recovery of function, whether after injury or as in response to disease. In our research training program, we will use a new animal model to address neural reorganization in the visual circuit. The fish Astyanax mexicanus provides a particularly novel window into network remodeling because it is extant in two readily available forms: a visual river-dwelling (surface fish) form and a cave-dwelling form (cavefish). It is closely related to zebrafish, and all techniques use in this zebrafish can be used in Astyanax. Adult cavefish lack eyes and the corresponding visual neural structures are severely reduced. Eye development is nevertheless initiated during embryogenesis, but later arrests with the lens undergoing programmed cell death and the rest of the eye degenerating and sinking into the orbit. However, it is possible to rescue the eye, and the corresponding visual circuits, by transplanting an embryonic surface fish lens into a degenerating cavefish eye. We will use neuroanatomy, behavior and calcium imaging to measure the changes that occur in the brains of blind cavefishes after developmental manipulation. Our central hypothesis is that the developing optic tectum circuitry in the cavefish is robust and receptive to coherent visual information, so that homeostatic mechanisms will allow for the emergence of visual codes. Our specific objective is to test the malleability of the optic tectum circuitry in response to visual input during development. To accomplish this, we will train two undergraduate students, one master's student and a PhD student as well as high school volunteers from a charter school in Newark, NJ.